Boot having a flexible outer wall

ABSTRACT

A ski boot having a rigid shell made of a plastic material, in which an inner comfort element is inserted, the rigid shell including a collar fixed on a shell base. The boot has a softening structure located on the outer wall of the boot and which includes a plurality of recesses provided in the rigid shell. The recesses are provided in the ankle joint zone, in the lower portion of the outer wall of the shell base, and on the outer wall of the collar.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent Application No. PCT/FR03/01273, having an international filing date of Apr. 22, 2003, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is hereby claimed under 35 U.S.C. §120.

This application is based upon French Patent Application No. 02.05527, filed Apr. 26, 2002, the disclosure of which is hereby incorporated by reference thereto in its entirety and the priority of which is hereby claimed under 35 U.S.C. §119.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a sports boot, in particular an alpine ski boot.

2. Description of Background and Relevant Information

For a long time, skiing techniques, whether in recreational use or in competition, have called for pressure to be applied mainly on the outer ski when turning, the pressure distribution being 80% or thereabouts for the outer ski, and 20% or thereabouts for the inner ski. In this so-called “classic” or “traditional” technique, the skier's leg positioned on the inside of the turn plays almost no role. This has caused the problems specific to the outside leg of the skier to have always been taken into account in the design of ski boots.

The advent of skis with parabolic sidecuts has led to the creation of a new skiing technique that completely distinguishes itself over the classic technique, and which is referred to as “wide track.” In this technique, the two skis with parabolic sidecuts each produce a curved directional effect; these two effects are complementary with one another, especially as the skier balances pressure between the inner ski and the outer ski relative to the turn. This new technique, which has already proven efficient, particularly in competition, forces the skier to maintain and apportion the pressure on the inner ski during the turn. It should be noted that the pressure on the ski positioned inside the turn occurs on the outer side of the foot that is located inside the turn.

The problem of apportioning the inner pressure is critical when performance is desired, Indeed, although the skier is supported on the inner ski, the skier should at all times be capable of lightening the pressure if too strong a pressure would cause the inner ski to skid. Thus, the new skiing technique weights the outer side of the foot, much more than the classic technique, for transmitting forces as well as for returning information and sensations. Moreover, although the morphology of the outer side of the foot is very different from that of the inner side, boots have always been designed so as to have equivalent rigidity on the inner and outer surfaces, the surfaces of the medial and lateral sides.

It is common for a ski boot to have a shell made of a plastic material, with a thickness that varies between 5 millimeters (mm) and 10 mm. Such thicknesses are necessary to guarantee the extreme rigidity of the inner surface thereof. Conversely, on the outer surface, such thicknesses make it very difficult for the slier to apportion inner pressure.

SUMMARY OF THE INVENTION

An object of the invention is to provide a ski boot, which enables the skier to apportion and maintain pressure on the inner ski relative to the turn.

Another object of the invention is to provide a ski boot that provides the skier with a wider range of movement for his/her foot, in particular a wider range of torsional movement thereof.

These objects are achieved by a ski boot that comprises a rigid shell, which can be made of a plastic material, and an inner liner, the outer wall of which is equipped with a softening structure so as to create, on the outer/lateral wall, a zone that is less rigid (i.e., more flexible) than the remainder of the boot, in particular less rigid than the inner/medial wall. Moreover, the softening structure is positioned in the force transmission zone of the outer/lateral surface.

The force transmission zone of the outer wall of the boot has three distinct and contiguous portions: the top portion that connects the upper edge of the boot to the ankle joint zone, the intermediate portion constituted by the ankle joint zone, and the lower portion that connects the ankle joint zone to the sole. In this latter portion, various transmission circuits radiate from the ankle joint zone to join either the front of the boot or the heel thereof, or yet a point located between these two extremes. During the various skiing phases, the transmission of forces follow different transmission circuits in this latter portion. At the end of the turn, for example, the skier is supported at the rear, and the general transmission circuit extends downward from the upper edge of the shell to a zone of the sole located in the area of the heel. At the start of the turn, or when the turn is initiated, the skier's pressure shifts forward, and the transmission circuit extends downward from the upper edge to the front of the sole,

The softening structure can be comprised of a plurality of juxtaposed recesses, either through holes or depressions not extending completely through the wall, provided in the rigid shell of the boot.

In a preferred embodiment of the invention, these recesses are provided in the area of the instep, in a zone separating the central closure mechanism and the area of the sole that supports the plantar arch.

In another preferred embodiment, the boot has a shell base and a collar, and the softening structure is uniformly arranged in an L-shaped weakened zone, the top portion of which is arranged on the outer surface of the collar, the intermediate portion and the lower portion being arranged on the outer surface of the shell base. The lower portion extends between the ankle joint zone and the sole; it extends up to the metatarsophalangeal flexion zone,

In other alternative embodiments of the invention, the softening structure is not arranged over the entire transmission zone of the outer surface, but only over a portion, such as in the area of the ankle joint or in the lower portion of the outer surface of the boot.

In a particular embodiment, the softening structure is arranged in the middle of the outer surface of the shell base, in the region located between the ankle joint and the metatarsophalangeal flexion zone. The arrangement of the softening structure in this central zone makes it possible to substantially increase the range of torsional movement of the sole of the shell and, therefore, enables more ample torsional movements of the skier's foot.

The shell softening structure can comprise a plurality of openings arranged on the outer surface of the shell, or a smaller number of large openings that substantially constitute the contour of the zone to be weakened. These openings may or may not be through openings, i.e., they may or may not extend entirely through the thickness of the shell of the boot. The softening structure can also comprise an outer thickness of the boot that is made thinner than the inner thickness, or made out of a more flexible material than that of the inner thickness.

The invention can be applied to any type of alpine ski boot, in particular ski boots of the conventional type, i.e., those with structures for insertion and removal of the foot at the front of the boot, but also rear-entry ski boots. The invention applies to any type of alpine skiing, from competition where the shells are very rigid to recreational skiing where the shells are less rigid. In either case, the boot of the invention provides a skier with a mix of both power and comfort.

BRIEF DESCRIPTION OF DRAWINGS

The present invention also relates to the characteristics that will become apparent from the description that follows, with reference to the annexed drawings showing, by way of example, several embodiments of the inventions, as well as alternative embodiments, wherein:

FIG. 1 shows a perspective view of a boot according to a first embodiment of the invention;

FIG. 2 shows a view of the outer/lateral surface of the shell base of the boot according to the first embodiment of the invention;

FIG. 3 shows a view of the lateral surface of the collar of the boot according to the first embodiment of the invention;

FIG. 4 shows a front view of a skier making a right turn;

FIGS. 5 and 6 show alternative embodiments of the invention in side views;

FIG. 7 and 8 show a shell base according to another embodiment of the invention;

FIG. 9 shows a rear-entry ski boot according to an embodiment of the invention;

FIGS. 10 and 11 show a boot according to another embodiment of the invention;

FIG. 12 shows a cross-sectional view of a composite element that can be integrated into the shell base described in FIG. 2; and

FIGS. 13, 14, and 15 are side views of other embodiments of the invention.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a boot 1 according to the invention, the boot having four buckles in the illustrated embodiment. The boot 1 has a shell that is divided into two: main portions, the shell base 2 and the collar 3. An inner comfort element in the form of a removable liner 4 is inserted inside the shell. The shell base 2 is made by molding a thermoplastic material, such as polyurethane. Therefore, this is a unitary or one-piece structure that is comprised of a sole portion 5 and an upper portion. The sole portion is equipped at the front and at the rear with standardized end pieces provided to cooperate with a binding device, The binding device connecting the boot to the ski can be of any known type, including in particular a central binding device or the like.

The upper portion of the shell base 2 is open at the top for the passage of the foot into or out of the boot and further has a pair of flaps arranged above the foot in order to facilitate putting on and tightening the boot 1 on the user's foot. Two buckle mechanisms 6, 7 are arranged on the shell base 2. The front buckle mechanism 6 is arranged in the area of the metatarsophalangeal joint of the foot of the skier, whereas the central mechanism 7 is positioned in the area of the instep. They each have a pallet that is pivotally mounted on a cap, which is fixed on the lateral flap; an articulated buckle is connected to the pallet by means of a boot strap. A toothed rack adapted to receive and retain the buckle is fixed in front of the cap and on the medial flap. The sizes of the outer flap and the inner flap are such that they overlap one another, Furthermore, a joint ensures that the connection of the two flaps is impervious, i.e., waterproof.

The shell base 2 covers the user's foot up to the ankle joint. Holes are provided in the shell base 2, in the area of the ankle joint, one of the holes being provided on the outer side, or lateral side, of the upper, another hole being provided on the inner side, or medial side. The outer hole 8 and the inner hole are substantially arranged along the axis of the ankle joint. The two aforementioned holes cooperate with corresponding holes provided at the base of the collar, as well as with rivets or other connectors for connecting the collar to the shell base.

The softening structure is uniformly distributed over a wide portion of the lateral (little-toe) side of the shell, defining a substantially L-shaped weakened zone 9. The lower portion 10 of this L-shaped zone is longitudinal; it starts in the area of the front of the boot and extends up to the metatarsophalangeal articulation zone, or approximately thereto. The height of the zone 9 is generally defined heightwise by the sole 5, on the one hand, and by the fastening points of the buckle mechanisms 6, 7, on the other hand. The intermediate portion 11 of the L-shaped zone is located in the extension of the lower portion 10, and is generally oriented more vertically than the latter. It is positioned so as to cover the area of the ankle joint. Finally, the top portion 12 extends from the intermediate portion 1 up to the area of the upper edge of the collar 3.

The L-shaped zone 10 corresponds to a lateral outer zone for transmitting forces from the top of the boot down to the sole, in particular to the metatarsophalangeal articulation zone and to all of the zones of the sole located forward of the heel zone.

FIG. 2 shows in detail the lower portion 10 and the intermediate portion 11 of the softening structure that is provided on the shell base 2. They comprise or, in the illustrated embodiment, they are constituted by, a plurality of hexagonal recesses 13 nested in one another, somewhat like a honeycomb structure. The weakened zone 9 grouping all of the recesses 13 originates from the front of the boot, substantially in the area of the metatarsophalangeal articulation zone. Its width increases progressively so as to reach a maximum in the area of the ankle joint. Recesses are provided on both sides of the outer hole 8 that is present in the shell base and is used for fixing the collar 3 thereon. Each of the recesses 13 has a diameter of approximately 15 mm, and the recesses are spaced apart by a distance between 3 and 10 mm, or, in a particular embodiment, 5 mm. In the illustrated embodiment, the recesses are through recesses, and means guaranteeing the imperviousness of the shell base are provided. These means can take the form of a film, for example, or other barrier that is fixed to the inside of the shell base, or a foam-type filling material. In the embodiment shown in FIG. 2, the means guaranteeing imperviousness are constituted by a transparent film made of a material that is compatible with the polyurethane (PU) used for the shell, the film being positioned in the mold prior to injection.

Other modes of attachment can be used, such as adhesives, for example. Furthermore, the imperviousness means can be coupled to ventilation means or insulating means. An example of a combined arrangement for both imperviousness and insulation is shown in FIG. 12. Shown is a composite element 33 that includes two impervious plastic films 29 a, 29 b between which a foam layer is positioned. The two plastic films 29 a, 29 b are pressed against one another in all of the zones where the composite element is in contact with the inner surface of the shell, In the remaining zones, the form maintains all of its thickness. When this element is assembled with the remainder of the shell, the voluminous portions 31 are nested in the recesses. In addition to its sealing function, the filling material can have a shock absorption function. The contour of the recesses 13 does not need to be hexagonal. Other shapes are encompassed within the context of the invention.

Furthermore, the recesses need not be through recesses, provided that their depth with respect to the thickness of the shell, in the area where they are arranged, is such that the zone in question is substantially weakened. Advantageously, non-through recesses do not require any additional imperviousness means.

FIG. 3 shows the collar of a boot according to the invention. It is equipped with two buckle mechanisms 15, 16, and a flexible strap 14. The softening structure comprises two openings 17, one of which is located between the two buckle mechanisms 15, 16, and the second of which is located between the upper buckle mechanism 16 and the flexible strap 14. A flexible film adhered to the inside of the collar makes it possible, among other things, to guarantee the imperviousness thereof.

The functioning of the ski boot according to the invention can be described as follows. FIG. 4 shows a skier making a right turn. The force that he transmits to the outer ski relative to the turn passes through his left leg and through the inner surface of the left boot. The force that he transmits to the inner ski 19 relative to the turn passes through his right leg, which is bent, and through the outer surface 24 of the right boot. The pressure exerted on the outer ski 18 is relatively strong; the pressure of the inner ski 19, however, is lighter, relative to the turn, as it is more directly controlled and apportioned by the skier's foot.

The boot according to the invention, then, is constructed in a way that takes into account the aforementioned forces, such as the different forces that are exerted on the inside and outside boots during a turn, and the recognition of modern skiing style and stance, such as, for example, facilitating a two-footed race technique, in which the inside foot is edged and powered against the snow aggressively, as is the outside foot, For example, the softer external side of the boot of the invention promotes faster, more fluid edge changes and tolerance even on harder snow, as well as enhancing the skier's sensations from the boot's external side. The more rigid internal side provides precision, power, and speed, i.e., sharp-driving performance.

A boot according to the invention, compared to boots with stiffer external sides, tends to abate edge chatter and vibration, so that one's skis' performance and stability are not compromised. A boot constructed according to the invention also improves the ability of a skier to hold a solid edge and to make quick/sharp turns.

FIGS. 5 and 6 show two alternative embodiments of the invention.

The shell base 21 of FIG. S has a weakened zone that is limited to the area corresponding to the ankle joint, whereas the lower portion of the outer surface of the shell base retains all of its rigidity. Such a shell base can be associated with a conventional collar, or with a collar such as shown in FIG. 3.

The shell base 22 of FIG. 6 has a weakened zone that is limited to the lower portion of the outer/lateral wall of the shell base.

FIGS. 7 and 8 show a shell base 2 according to another embodiment of the invention, in which the weakened zone 9 is a recessed zone. As can be seen, perhaps more vividly in FIG. 8, the recessed zone does not extend completely through the thickness of the wall of the boot. It is common for a ski boot to have a shell made of plastic, with a thickness that varies between 5 mm and 10 mm, or between approximately 5 mm and 10 mm. It is generally at the shell base, on the outer and inner surfaces, that the most substantial thicknesses are found. In this particular embodiment, the thickness of the weakened zone 9 is less than 60% of the thickness of the corresponding zone of the inner surface 23. By corresponding zone is meant a zone located on the inner surface that is positioned symmetrically relative to the weakened zone with respect to the median plane of the boot.

FIG. 9 shows another embodiment of the invention. The ski boot is a so-called rear-entry boot. The shell therein comprises a shell base 2, a cuff 25 fixed on the shell base, and an articulated rear spoiler 26 that opens up so as to allow foot insertion and removal. The softening structure is positioned on the shell base; on the one hand, and on the cuff, on the other hand. On the shell base, an oblong recess is provided in the shell, resulting in a thinning of the shell by approximately 50%. Two recesses are provided on the cuff, on the lateral surface thereof, on both sides of a closure 27 used to block the spoiler 26 in the closed position.

FIGS. 10 and 11 show another embodiment of the invention. The ski boot 1 has a shell base 2 and a collar 3. The boot has a substantial asymmetry between its inner surface 23 and outer surface 24. FIG. 11 is a cross-section of the shell base 2 along the plane XI-XI of FIG. 10, and shows that the thickness of the outer surface 24, from the sole 5 up to the end of the outer flap 28, is substantially half that of the inner surface 23. Similarly, the collar 3 has an asymmetry between the inner overlap and the outer overlap, which is thinner.

A variation of the boots shown in FIGS. 7 and 10 involves the manufacture of the shell base and/or of the collar by dual-material molding, the material of the weakened zone or of the lateral wall being more flexible than that of the medial wall, in particular that of the corresponding zone of the medial wall.

FIG. 13 shows a side view of another embodiment of the invention. The shell of an alpine ski boot is shown therein, which comprises two main portions, a shell base 2 and a collar 3. The outer/lateral wall of the shell base 2 is equipped with a softening structure that comprises non-through recesses 13 arranged in the central zone of the outer/lateral wall of the shell base 2, between the sole and the buckle mechanism for tightening the instep 7. The inner/medial wall of the boot, not visible in the figure, is not provided with the same softening structure, and there is a difference in rigidity between the outer and inner walls of the shell. In the weakened zone, the recesses 13 have a hexagonal shape and are uniformly juxtaposed. In addition to the weakening of the outer/lateral wall, the arrangement of the softening structure in the central zone also softens the sole of the shell in torsion. A comfort liner (not shown) is to be inserted inside the shell, as is known in the art.

FIG. 14 shows a side view of another embodiment of the invention, in which the recesses 13 have a rounded shape and are juxtaposed along a grid, one of the directions of which is defined by a straight line connecting the axis of the ankle joint and the front tip of the boot, whereas the other connects the articulation axis to the sole, in front of the heel, along a slightly oblique straight line.

FIG. 15 shows another embodiment of the invention, in which the lower rigidity zone comprises a series of slits 32 that are substantially parallel to one another and each oriented along a direction that is substantially perpendicular to a transmission circuit extending from the articulation axis to the metatarsophalangeal flexion zone. Each of these slits 32 can be slightly arched or curved, as shown, with a concavity oriented upward.

The invention is not limited to the detailed embodiments described herein by way of example In particular, the invention encompasses any ski boot in which a substantial asymmetry in rigidity exists between the outer and inner walls due to a softening of the outer wall. For example, instead of the recesses of the softening structure being simply either through holes or depressions, not extending through the lateral wall of the shell, such recesses, holes, and depressions, could be partially or completely filled with plastic or rubbery material.

LIST OF REFERENCES

-   1—Boot -   2—Shell base -   3—Collar -   4—Liner -   5—Sole -   6—Buckle mechanism (metatarsophalangeal zone) -   7—Buckle mechanism (instep) -   8—Outer hole -   9—Weakened zone -   10—Lower portion -   11—Intermediate portion -   12—Top portion -   13—Recesses -   14—Flexible strap -   15—Buckle mechanism -   16—Buckle mechanism -   17—Openings -   18—Outer ski -   19—Inner ski -   21—Shell base -   22—Shell base -   23—Inner surface -   24—Outer surface -   25—Cuff -   26—Spoiler -   27—Closure -   28—Outer flap -   29 a, 29 b Plastic film -   30—Foam -   31—Voluminous portion -   32—Slit -   33—Composite element 

1. A sports boot comprising: a rigid shell including a lateral wall and a medial wall; an inner liner; a structure for softening a force transmission zone of the lateral wall of the shell, said force transmission zone extending from an upper edge area of the shell to a sole area of the boot, said force transmission zone further extending between a front tip of the shell and a heel area of the shell, said softening structure providing a difference in rigidity between the lateral wall and the medial wall of the shell.
 2. A sports boot according to claim 1, wherein: the softening structure comprises a plurality of juxtaposed recesses provided in the shell.
 3. A sports boot according to claim 2, wherein: the softening structure comprises a zone of the lateral wall, the lateral wall having a thickness less than 60% of a thickness of a corresponding zone of the medial wall.
 4. A sports boot according to claim 1, wherein: the softening structure comprises a zone of the lateral wall made of a material more flexible than a material of the remainder of the boot and more flexible than a material of a corresponding zone of the medial wall.
 5. A sports boot according to claim 1, wherein: the softening structure is provided in the lateral wall of the shell, in an area of the user's instep.
 6. A sports boot according to claim 1, wherein: the softening structure is provided in an area of the axis of the user's ankle joint.
 7. A sports boot according to claim 1, further comprising: a collar fixed on a shell base and equipped with at least two closure mechanisms; a softening structure being arranged on the outer wall of the collar having at least one opening positioned between the closure mechanisms.
 8. A sports boot according to claim 1, wherein: the recesses extend through a thickness of the shell; an imperviousness structure is arranged on the inner surface of the shell so as to seal said recesses.
 9. A sports boot according to claim 8, wherein: said imperviousness structure includes a thermal insulating layer.
 10. A sports boot according to claim 1, wherein: the boot is a ski boot.
 11. A sports boot according to claim 1, wherein: the rigid shell is made of a plastic material. 